Make ParentMap work with explicit specializations of function templates.

For an explicit specialization, we first build a FunctionDecl, and then
we call SubstDecl() on it to build a second FunctionDecl, which has the
first FunctionDecl as canonical decl.

The address of an explicit specialization of function template used to be the
canonical decl of the FunctionDecl.  This is different from all the other
DeduceTemplateArguments() calls in SemaOverload, and since the canonical decl
isn't visited by ParentMap while the redecl is, it also made ParentMap assert
when computing the parent of a address-of-explicit-specialization-fun-template.

To fix, remove the getCanonicalDecl() call.  No behavior difference for clang,
but it fixes an assert in ParentMap (which is e.g. used by libTooling).

llvm-svn: 260159

2 files changed, 7 insertions, 1 deletions

diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index eaac06162f7..d71b307d15b 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -10339,7 +10339,6 @@ private:
     // Template argument deduction ensures that we have an exact match or
     // compatible pointer-to-function arguments that would be adjusted by ICS.
     // This function template specicalization works.
-    Specialization = cast<FunctionDecl>(Specialization->getCanonicalDecl());
     assert(S.isSameOrCompatibleFunctionType(
               Context.getCanonicalType(Specialization->getType()),
               Context.getCanonicalType(TargetFunctionType)));
diff --git a/clang/unittests/ASTMatchers/ASTMatchersTest.cpp b/clang/unittests/ASTMatchers/ASTMatchersTest.cpp
index 2aaa92c35b8..5578e066a22 100644
--- a/clang/unittests/ASTMatchers/ASTMatchersTest.cpp
+++ b/clang/unittests/ASTMatchers/ASTMatchersTest.cpp
@@ -4333,6 +4333,13 @@ TEST(HasAncestor, NonParmDependentTemplateParmVarDeclRefExpr) {
                       declRefExpr(to(decl(hasAncestor(decl()))))));
 }
 
+TEST(HasAncestor, AddressOfExplicitSpecializationFunction) {
+  EXPECT_TRUE(matches("template <class T> void f();\n"
+                      "template <> void f<int>();\n"
+                      "void (*get_f())() { return f<int>; }\n",
+                      declRefExpr(to(decl(hasAncestor(decl()))))));
+}
+
 TEST(HasParent, MatchesAllParents) {
   EXPECT_TRUE(matches(
       "template <typename T> struct C { static void f() { 42; } };"